Decorative light source



1965 M. THAU ETAL DECORATIVE LIGHT SOURCE Filed Dec. 13, 1960 UnitedStates Patent 3,20tl,2$0 DECORATIVE LIGHT SQURCE Marcus Than and FrancesKrasnow Than, New York, N.Y. (both Universal Gratings Inc., Ave. C,Newark 5, NJ.)

Filed Dec. 13, 1960, Ser. No. 75,554 SCiaims. (Cl.313--110) Thisinvention relates to decorative light effects, and more particularly tolamps provided with a transparent decorative finish.

Decorative electric light bulbs are a staple article of commerce. Theirdecorative effect may be due to the overall shape of the glass envelopewhich encloses the actual light source, such as an incandescentfilament, or to the texture of the glass envelope. Fluted glass bulbshave been previously employed, and plain glass envelopes have beencoated to produce special effects.

This invention in its more specific aspects is concerned with a coatedtransparent envelope for a light source. The known decorative coatingson electric light bulbs rely on selective transmission of light. Theselection may be made among the light waves of different wave lengths soas to transmit only light of selected colors, or different areas of thebulb surface may be coated with material of different opacity so as totransmit light of different intensity. It is a common feature of theknown decorative coatings for electric light bulb envelopes that theyreduce the light output of the bulb to a significant extent. It is anobject of this invention to provide a decoratively coated light bulb thelight output of which, if so desired, is not significantly smaller thanthe output of the bulb without the coating.

We aim specifically at a decorative light source the effect of which iproduced by varying the refractive properties of the lamp envelopes overthe surface thereof whereby the intensity of the light emitted variesover the surface of the bulb, but the overall light output may remainvirtually unchanged.

Lenses arranged about a light source have previously been employed toproduce an effect somewhat related to that produced by this invention,but a lens arrangement is of necessity so costly as to preclude itsapplication in most cases. Also we are concerned more specifically witha decorative bulb which produces an effect not readily duplicated bylenses unless they be numerous and very small.

We have found that a decorative incandescent light bulb obtained whenthe clear glas enevelope of an ordinary bulb is coated with asubstantially transparent wrinkle-textured organic coating ofessentially uniform composition. The terms wrinkle-texture andwrinklecoating have'acquired specific meanings in paint technology, andwill be employed in this specification and the appended claims as theyare understood by paint technologists.

The decorative lamp obtained shows very bright surface areas or spotsseparated by darker areas For lack of a more descriptive term, thedecorative effect will be referred to hereinafter as sparkle to expressthe brilliance of the individual light spots which normally exceeds theaverage brightness of the bulbv surface when not provided with thewrinkle textured coating. It will be understood that there cannot be anyeffect comparable to that of sparks which would imply a variation oflight intensity in time.

Wrinkle finishes are generally produced by applying a layer of asuitable liquid coating'composition to a sur face. The layer .ispermitted to dry with or without the application of heat. Internalstresses developing during the drying operation cause small ridges toform on the previously smooth surface of the coating. When the coatingcomposition is substantially transparent in the dry condition and isdeposited on a transparent carrier through which light is transmitted,the individual ridges have been found to act as minute lenses and toproduce a sparkling effect.

The configuration of the ridges and the resulting overall pattern of thewrinkle textured coating depends partly on the chemical nature of thecoating composition in a manner which is not fully understood as to itstheoretical basis, but a large amount of data based on practicalexperience is now available which permits those skilled in this art toinfluence the fineness of the pattern, and to some extent also the shapeof the ridges. An even greater influence on the appearance of thewrinkle pattern is exerted by the shape of the coated surface.Substantially cylindrical surfaces favor the establishment of a patternin which fairly uniform elongated ridges extend parallel to the cylinderaxis. On a spherical or otherwise threedimensionally curved surface, thesame coating composition will produce a pattern of small unit areas. Ineach area the ridges follow an approximately parallel course, but thedirections of main longitudinal extension of the ridges in adjacentareas are angularly offset in a random pattern. The overall appearanceof a spherical bulb coated with a wrinkle finish is quite uniform. On aflat surface the pattern of ridges may approach more closely a honeycombstructure in which the ridges are connected and are of somewhatirregular polygonal shape.

Regardless of the specific configuration of the ridges, a transparentwrinkle textured organic coating intersecting a beam of light producesthe decorative sparkle effect desired. It will be understood thatquantitative differences in the decorative effect will be brought aboutby varying the spacing of the ridges and their height. As the ridges areflattened by reducing their height and increasing their spacing, thedifferences in refractive properties between the ridges and theintervening furrows are reduced and the sparkle effect is diminished.

The exact nature of this invention as well as other objects andadvantages thereof will be readily apparent from consideration of thefollowing specification relating to the annexed drawing in which thesole figure shows a conventional light bulb having a standard screwsocket 1 providing two terminal connections for a fila- 'ment 2. Thefilament is enclosed in a gastight clear glass envelope 3 ofsubstantially spherical shape which is shown partly broken away toreveal the filament.

The glass envelope 3 is completely coated on the outside with a layer 4of transparent wrinkle textured organic coating composition. The lightbulb is shown full scale and its spherical portion ha a diameter ofapproximately 2- /2 inches. The wrinkle pattern is composed of unitareas having each a main dimension of less than /8 inch. The spacing ofindividual ridges in each area is less than inch, but it will beunderstood that the size of the individual unit areas varie appreciablyover the bulb surface and the spacing of the ridges is quite irregular.The figures cited are merely representative average figures.

The coating is produced, for example, by dipping the clear glassenvelope of the bulb in the coating composition described hereinafter inmore detail in Example I, draining off an excess of coating material,and baking the coated bulb for 15 minutes at 300 F.

We have found that the sparkle effect which becomes apparent when thefilament 2 is connected to a suitable source of electric current doesnot depend on the nature of the transparent coating composition, on themanner in which it is applied, nor on any specific wrinkleconfiguration. Actually, it appears reasonable to assume that a similareffect could be produced by imparting a wrinkle texture to the glasssurface of the bulb itself.

The following examples of coating compositions are merely illustrativeof those which will lend themselves to the purposes of this invention.

Example I A wrinkling varnish base is prepared from a mixture of 100pounds of rosin-modified phenol formaldehyde (85% rosin, 15% B-stagephenol formaldehyde) with gallons of raw China-wood oil by heating themixture to 540 F. After two hours, a sample is withdrawn from the batch,cooled, and diluted with an equal amount of xylol. 5% by weight of theresin solids of a cobalt napthenate drier is added and a sample metalpanel is coated with the varnish. After drying, the coated panel isheated for one hour to 275 F. while the developing wrinkle pattern isinspected. If it is not considered satisfactory, heating of the mainbody of resin mixture to 540 F. is continued until the varnish reachesproper wrinkling properties after 5 /2 hours.

The batch of varnish is permitted to cool and is then diluted with anequal weight of xylol to form a stock solution. To prepare a bulbcoating solution, the stock solution is mixed with 2 /2% of a cobaltnaphthenate drier containing 6% cobalt, and diluted with a solvent tothe desired viscosity.

Blown China-wood oil may be substituted in 'the coating composition forraw China-wood oil, and other wrinkling oils, that is, oils known toimpart wrinkling properties to otherwise non-wrinkling varnishes may besubstituted for the China-wood oil without basically affecting theresults achieved although China-wood oil gives most consistentlysatisfactory results. Examples of such wrinkling oils are bodiedoiticica oil, the blown forms of perilla oil or linseed oil, also Poyokoil. The proportions of wrinkling to non-wrinkling constituents may bealtered to suit specific operating conditions and to vary the wrinklepattern produced in a manner well known in itself.

Example 11 An alkyd resin solution is prepared in a basicallyconventional manner by heating a mixture of Percent Phthalic anhydride28.4 Glycerol 17.7 China-wood oil fatty acids 34.6 Linseed oil fattyacids 19.3

for several hours to 500 F. until the test described in Example Iindicates that the alkyd varnish produced has the desired wrinklingproperties. The time required may vary between approximately three andsix hours. The varnish is then cooled and mixed with an equal weight ofxylol or a mixture of xylol and toluol.

To produce a wrinkle coating composition, the alkyd stock is furthercompounded as follows:

Alkyd stock "percent" 66 Blown China-wood oil ozs. per gal 2 Cobaltnaphthenate drier do 3.2 A solvent mixture of equal parts of xylol andtoluol Balance This coating composition is further adjusted by additionsof xylol-toluol mixture (1:1) to a viscosity of 22 to 32 seconds on aNo. 4 Ford Cup, and sprayed on clear glass bulbs from a spray gun.

The coated bulbs are dried to remove most of the solvent, and then bakedat 275 F. for one hour, 300 F. for minutes, or in any approximatelyequivalent manner as is well known in itself.

Those skilled in paint technology will understand that the method ofapplication will largely govern the viscosity of the coating compositionemployed. It is also well known that the viscosity of the liquidmaterial as applied influences the wrinkle pattern that becomes apparenton drying or curing of the coating. A coating composition of higherviscosity usually forms a coarser wrinkle pattern, and vice versa.

We consider a fine wrinkle texture most pleasing, and therefore preferto apply coatings by spraying of compositions having a viscosity near 22seconds. Dipping compositions will generally produce a fine-texturedwrinkle finish from a viscosity of approximately 32 to 35 seconds, but aserviceable coarse-textured wrinkle coating can be formed by dipping aclear glass bulb in a varnish having a viscosity of to seconds, andothers may prefer the appearance of a light source in which a rathercoarse wrinkle-textured film is interposed between a filament or thelike and the eyes of the viewer.

If desired, the coating composition may be colored to obtainparticularly pleasing effects at some sacrifice in light output. Thecoloring matter must be transparent or substantially transparent. Anopaque coating will interfere with the sparkle effect. Many dyes andpigments are available which lend themselves readily to coloring thevarnish bases described above. The following dyes are merelyillustrative of suitable coloring materials:

Auramine (Colour Index 655) Methylene Blue (Colour Index 922) MethyleneGreen B (Colour Index 924) Bismarck Brown R (Colour Index 332) Auramineis classified as a spirit soluble dyestuff, the others belong to theclass of basic dyestuffs. All are soluble in a mixture of 80% acetoneand 20% methanol in a concentration of 12 ozs. per gallon. The solutionof coloring matter is added to the varnish composition otherwise readyfor application to a light bulb in quantities sufficient to produce thedesired effect. A light blue coating is produced by adding 0.15 gram ofthe 12 oz. per gallon solution of Methylene Blue in acetone-methanol toone gallon of the varnishes of Examples I and II, and similar minuteamounts of the other dyestuffs will produce decorative color effects.

The proper selection of the coloring material will be influenced by thewattage output of the bulb to be coated, and by other properties of thebulb which influence the temperature reached by the glass envelope inservice. As a group, dyes are more susceptible to fading under heat thanpigments which will be discussed presently.

The appliction of the dyes enumerated will generally be limited toevacuated bulbs of low wattage, 25 watts being the approximate upperlimit of lamp output with which the fading of the dyes will bereasonably slow. On the other hand, the varnish described in Example Itends to yellow under the influence of excessive heat, and thisyellowing to some extent may be balanced by the fading of BismarckBrown, so that a combination of Bismarck Brown with the varnish ofExample I will be found to have a stable color under conditions ofintermediate wattage. Neither dyes as a class, nor the varnish ofExample I will generally be recommended for use with gas filled lampsthe glass envelopes of which operate at fairly high temperatures.

Data on heat resistance and solvent solubility of organic dyes areavailable and those skilled in the art will have no difiiculty insecuring suitable dyes for most applications. Under severe operatingconditions, we prefer to color a heat resistant varnish such as thealkyd varnish of Example H with transparent pigments of which thefollowing are illustrative:

Thioindigo Fast Red Phthalocyanine Blue (Copper) (Prototype 481)Phthalocyanine Green (Prototype 483) Hausa Yellow (Prototype 103)Quinacridone Red These pigments are not listed by the Colour Index,

but several of them have recognized prototypes. They are distinguishedby excellent resistance to heat and light and are virtually transparentin thin layers or when finely ground.

To incorporate a pigment in a wrinkling varnish, we grind the pigmentwith three to four times its weight of varnish stock until amacroscopically homogeneous smooth mixture is obtained and add asuitable amount of the resulting paste to the varnish. The depth ofcolor desired will determine the amount of pigment paste used. 3 ozs. ofa Phthalocyanine Blue paste containing of pigment will produce a mediumblue coating when added to one gallon of the varnish of Example II.

The transparent wrinkle varnishes employed for coating light bulbsaccording to this invention may be further modified by the addition ofnatural or synthetic pearl essence. A commercial pearl essence, whichiseither derived from fish scales or synthetic, consists of guaninecrystals suspended in a vehicle usually containing a resin and amylacetate or other solvent. Approximately 4 to 8 ozs. per gallon of pearlessence, corresponding to 1 to 3 ozs. of guanine per gallon may beincorporated into the varnishes of Examples I and II without materiallyaffecting the wrinkling properties of the coatings produced. Ifpreliminary tests should show that a commercial product is notadequately compatible with the wrinkle coating, guanine crystals may beground with varnish base to form a paste containing guanine.

Depending on the amount of pearl essence employed and/or the fineness ofthe wrinkle structure, the appearance of the bulb filament is more orless accentuated. The amount of pearl essence added must be less thanthat commonly employed to produce an actually pearlescent, more or lessopaque surface.

We prefer to use a synthetic pearl essence prepared by grinding leadhydwrogen phosphate (PbHBO crystals with a varnish base to produce apaste of approximately 40% lead hydrogen phosphate content. The paste isthen admixed to a wrinkle varnish having the same base in amounts of upto approximately 24 ozs. per gallon. There is no lower limit to theamount of lead hydrogen phosphate paste that may be incorporated in awrinkle varnish, but the elfect produced with amounts of less than about12 ozs. per gallon is so small as not to be of value in most instances.Quantities of more than 24 ozs. per gallon of lead hydrogen phosphatepaste do not show an increased effect commensurate with the largeramounts added, and will usually be unnecessary.

A portion of the lead hydrogen phosphate may be replaced by crystallinebasic lead carbonate at a saving in cost without a significant loss inefficiency. A pigment mixture which produces effects comparable toguanine when employed in small amounts consists of 40% lead hydrogenphosphate and 60% basic lead carbonate crystals.

It will be appreciated that dyestuffs, pigments, and pearl essence maybe added to the wrinkling varnishes in any conventional manner otherthan specifically described without departing from the spirit and scopeof this invention, and that the methods of mixing specificallydescribed, which are conventional in themselves, are merely intended tobe illustrative. The quantities of these addition agents also are notcritical in any manner, and the several addition agents may be usedseparately or jointly as desired. A wrinkling varnish may thus beprepared to contain simultaneously a dye or dye mixture, a pigment orpigment mixture, as well as pearl essence of natural or syntheticorigin, or both. The addition agents will modify tthe basic sparkleeffect produced by the transparent wrinkle textured coating, and theirmodifying eifects are basically additive.

The following basic varnishes have also been found to producetransparent wrinkle finishes on glass bulbs suitable for the decorativelight effects of this invention but the wrinkles produced with thefollowing compositions are relatively shallow and widely spaced.

Example Ill lbs. of rosin modified phenol formaldehyde resin are heatedwith 8 gallons of liquefied oiticica oil to a temperature of 500 to 510F. until a homogeneous dispersion is obtained. The mass is permitted tocool to a temperature of less than 350 F. whereupon five gallons ofxylol and 12 gallons of light gravity petroleum naphtha are added withstirring. The resulting mixture is cooled to a temperature notsubstantially above room temperature and is mixed at a ratio of 19:1with a 6% solution of manganese octoate in a mixture of aromaticsolvents.

Upon further dilution with a mixture of xylol and petroleum naphtha inan approximate proportion of 1:2 to give the desired viscosity, there isobtained a wrinkling varnish ready for application to a light bulb anddrying in the afore-described manner.

Example IV .A mixture of 4 lbs. polyvinyl butyral with 4 gallons ofbutanol and 1 gallon of water is prepared by thorough blending at roomtemperature. The mixture which contains air bubbles-is permitted tostand until the entrapped air escapes and is then ready for spraying. Ifdesired, it may be diluted by-further additions of aqueous butanol.Electric light bulbs sprayed with the polyvinyl butyral lacquer obtainedmay be air dried or force dried at elevated temperature.

After drying, the bulbs arefound to be coated with a relativelyshallow-ridge wrinkle finish in which the wrinkles are spaced almost A"apart. The sparkle effect observed when the bulb is connected to asource of electric current is correspondingly poor.

Example V Chlorinated rubber of 5 centipoise viscosity is dissolved inxylol in an amount of one pound per gallon. 6 lbs. of the resultingsolution are mixed at room temperature with 2 lbs. of blown China-woodoil and 0.22 lb. of a commercial cobalt drier containing 6% cobalt.There is obtained a wrinkle coating composition which may the applied inany desired manner. Its viscosity may be adjusted with xylol if sodesired.

A wrinkle finish of good texture is obtained by air drying a coatingdeposited on a light bulb, but a better wrinkle eilect is produced whenthe coating is force dried at elevated temperature, for example, at 250F. for approximately one hour.

The substantially colorless transparent wrinkle textured coatingsdeposited from these compositions in a manner analogous to that ofExamples I and II may be further modified by incorporating thereinsubstantially transparent coloring matter and nacreous substantiallytransparent pigments. The transparency of the addition agents isgenerally improved, if necessary, by grinding them to a small particlesize. Lead hydrogen phosphate thus is preferably ground very fine sinceit produces pearlescence and opacity by its crystalline structure whennot so ground. Lead hydrogen phosphate is most effective when employedin varnishes of relatively low refractive index, that is, lower than therefractive index of lead hydrogen phosphate. All the examples ofvarnishes enumerated in Examples I and II satisfy this requirement.

The strongest sparkle eifect is produced when the film of wrinkletextured transparent material transmits light that includes asubstantial proportion of aligned light rays, and as small as possible aproportion of diifuse light. Best results are thus obtained with a pointlight source spaced from the wrinkle textured film or by any othersource of parallel light rays. Virtually no sparkle effect is producedwhen the film is directly applied to a source of diffuse light, such asan externally frosted bulb or a conventional fluorescent tube. When awrinkle coating is deposited on a flat glass carrier and a distant lightsource of any nature is viewed through the carrier, the decorativesparkle is clearly observed. Generally then, sparkle can be producedwith a source of diffused light by spacing it from the film.

The term varnish as employed in this specification and the appendedclaims is to be construed broadly and it is not limited to any specificclass of organic coating compositions nor to any specific curingreaction of the composition. The term wrinkle varnish will thus beunderstood to designate any organic finishing composition from which awrinkle textured coating can be produced by the usual methods ofapplication, such as spraying, brushing, dipping, roller coating, knifecoating, or the like, followed by drying and/or heating.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically disclosed.

What we claim is:

1. A decorative electric light bulb comprising a light transmittingrigid envelope; a substantially transparent coating of wrinkle texturedorganic material of uniform composition on said envelope, said coatinghaving an outer surface formed with a plurality of spaced integralridges, said ridges being elongated in substantially parallel alignment;and a light source within said envelope.

2. A bulb as set forth in claim 1, wherein said coating is colored.

3. A bulb as set forth in claim 1, wherein said coating includes anacreous pigment.

4. A decorative light source comprising, in combination:

(a) a light emitting member adapted to produce a beam of light includingat least a major portion of substantially aligned light rays, and notmore than a minor portion of diffuse light rays;

(b) a substantially transparent carrier intersecting said beam; and

(c) a wrinkle-textured substantially transparent coating of uniformcomposition on said carrier, said coating having an outer surface formedwith a plurality of spaced integral ridges, said ridges being elongatedin substantially parallel alignment.

5. A light source as set forth in claim 4, wherein said member is anincandescent filament, and said carrier is a transparent portion of asubstantially gas tight envelope enclosing said filament, saidtransparent portion being spaced from said filament.

DAVID J. GALVIN, Primary Examiner.

ARTHUR GAUS S, JAMES D. KALLAM, GEORGE N.

WESTBY, Examiners.

1. A DECORATIVE ELECTRIC LIGHT BULB COMPRISING A LIGHT TRANSMITTINGRIDIG ENVELOPE; A SUBSTANTIALLY TRANSPARENT COATING OF WRINKLE TEXTUREDORGANIC MATERIAL OF UNIFORM COMPOSITION ON SAID ENVELOPE, SAID COATINGHAVING AN OUTER SURFACE FORMED WITH A PLURALITY OF SPACED INTEGRALRIDGES, SAID RIDGES BEING ELONGATED IN SUBSTANTIALLY PARALLEL ALIGHMENT;AND A LIGHT SOURCE WITHIN SAID ENVELOPE.